FIG. 9 is an electrical diagram of a conventional angular velocity sensor, and FIG. 10 shows first and second driving electrodes and a sensing electrode in this conventional sensor when viewed from the above.
As shown in FIG. 9, the conventional angular velocity sensor includes drive circuit 1, detection device 2, and detection circuit 3. Detection device 2 vibrates in response to drive signals from drive circuit 1. Detection circuit 3 extracts a response signal from sensing electrode 8 of detection device 2, and outputs the signal. The sensor further includes signal processing circuit 4 and output circuit 5. Signal processing circuit 4 extracts an angular velocity sensing signal from the response signal and outputs the angular velocity sensing signal. Output circuit 5 includes output terminal 5A through which the angular velocity sensing signal from signal processing circuit 4 is outputted. Detection device 2 includes monitor electrode 99, which is connected to monitor circuit 90 for outputting a monitor signal. The monitor signal is used, for example, to control the amplitudes of drive signals in drive circuit 1 or to detect signals in signal processing circuit 4.
As shown in FIG. 10, detection device 2 includes first and second driving electrodes 6 and 7, and sensing electrode 8. Drive circuit 1 inputs a first drive signal to first driving electrode 6, and a second drive signal having a polarity opposite to that of the first drive signal to second driving electrode 7, thereby vibrating detection device 2.
An example of a conventional technique related to the present invention is shown in Patent Literature 1 shown below.
Such conventional angular velocity sensors have a problem that their angular velocity sensing signals have low detection accuracy. More specifically, in the above-described conventional sensor, the angular velocity sensing signal has noise by the influence of parasitic capacitance 9A between first driving electrode 6 and sensing electrode 8, and parasitic capacitance 9B between second driving electrode 7 and sensing electrode 8. As a result, the angular velocity sensing signal has low detection accuracy.